Such a sealing arrangement is known from U.S. Pat. No. 6,893,052 which is incorporated herein by reference. In the sealing arrangement disclosed in this patent, the plastic cap is arranged between the sealing faces and holds the sealing ring in position. The plastic cap and one of the coupling pieces are configured such that the plastic cap can simply be fastened between the sealing faces, even before the coupling pieces are screwed together. To this end, one of the coupling pieces has a radial peripheral projection oriented outwardly in the external region of the sealing face. The correspondingly configured plastic cap is clipped onto this radial peripheral projection.
During dismantling, the plastic cap has to be levered out by a tool. This involves the risk that the sealing faces of the coupling piece become scratched. The levered-off plastic cap should not be used after disassembly, but can only be differentiated from a new cap with the greatest difficulty so that confusion may result with the unwanted result that the old cap is used again.